From an abundance matrix (numbers of individuals of a given species at a site) returns a relative abundance matrix (proportion of individuals of a given species at a given site). This function works also with sparse matrices.
make_relative(abund_matrix)abundance matrix, with sites in rows and species in columns.
Similar shaped matrix as the input but with relative abundances instead
data("aravo", package = "ade4")
# Site-species matrix
mat = as.matrix(aravo$spe)
head(mat)[, 1:5] # Has absolute abundances
#> Agro.rupe Alop.alpi Anth.nipp Heli.sede Aven.vers
#> AR07 0 0 0 0 0
#> AR71 0 0 0 0 0
#> AR26 3 0 1 0 1
#> AR54 0 0 0 2 0
#> AR60 0 0 0 0 0
#> AR70 0 0 0 0 0
rel_mat = make_relative(mat)
head(rel_mat) # Relative abundances
#> Agro.rupe Alop.alpi Anth.nipp Heli.sede Aven.vers Care.rosa Care.foet
#> AR07 0.00000000 0 0.00000000 0.00000000 0.00000000 0.06666667 0
#> AR71 0.00000000 0 0.00000000 0.00000000 0.00000000 0.08695652 0
#> AR26 0.08108108 0 0.02702703 0.00000000 0.02702703 0.05405405 0
#> AR54 0.00000000 0 0.00000000 0.08695652 0.00000000 0.08695652 0
#> AR60 0.00000000 0 0.00000000 0.00000000 0.00000000 0.00000000 0
#> AR70 0.00000000 0 0.00000000 0.00000000 0.00000000 0.09375000 0
#> Care.parv Care.rupe Care.semp Fest.laev Fest.quad Fest.viol Kobr.myos
#> AR07 0.00000000 0.20000 0.00000000 0 0.13333333 0.00000000 0.06666667
#> AR71 0.04347826 0.00000 0.00000000 0 0.00000000 0.00000000 0.13043478
#> AR26 0.00000000 0.00000 0.02702703 0 0.08108108 0.02702703 0.10810811
#> AR54 0.00000000 0.00000 0.00000000 0 0.04347826 0.00000000 0.04347826
#> AR60 0.00000000 0.00000 0.00000000 0 0.23076923 0.07692308 0.07692308
#> AR70 0.03125000 0.03125 0.00000000 0 0.00000000 0.00000000 0.12500000
#> Luzu.lute Poa.alpi Poa.supi Sesl.caer Alch.pent Alch.glau Alch.vulg
#> AR07 0.00000000 0.06666667 0 0.00000000 0 0.00000000 0
#> AR71 0.00000000 0.08695652 0 0.00000000 0 0.00000000 0
#> AR26 0.02702703 0.00000000 0 0.00000000 0 0.02702703 0
#> AR54 0.00000000 0.08695652 0 0.04347826 0 0.00000000 0
#> AR60 0.00000000 0.00000000 0 0.07692308 0 0.00000000 0
#> AR70 0.00000000 0.06250000 0 0.03125000 0 0.00000000 0
#> Andr.brig Ante.carp Ante.dioi Arni.mont Aste.alpi Bart.alpi Camp.sche
#> AR07 0 0.00000000 0 0 0 0.00000000 0.00000000
#> AR71 0 0.04347826 0 0 0 0.04347826 0.04347826
#> AR26 0 0.02702703 0 0 0 0.00000000 0.02702703
#> AR54 0 0.00000000 0 0 0 0.00000000 0.04347826
#> AR60 0 0.00000000 0 0 0 0.00000000 0.07692308
#> AR70 0 0.03125000 0 0 0 0.03125000 0.03125000
#> Card.alpi Cera.stri Cera.cera Leuc.alpi Cirs.acau Drab.aizo Drya.octo
#> AR07 0 0.00000 0 0 0 0.00000000 0.00000000
#> AR71 0 0.00000 0 0 0 0.00000000 0.04347826
#> AR26 0 0.00000 0 0 0 0.00000000 0.00000000
#> AR54 0 0.00000 0 0 0 0.04347826 0.00000000
#> AR60 0 0.00000 0 0 0 0.00000000 0.00000000
#> AR70 0 0.03125 0 0 0 0.00000000 0.03125000
#> Erig.unif Gent.camp Gent.acau Gent.vern Geum.mont Omal.supi Andr.vita
#> AR07 0.00000000 0 0.00000000 0.00000000 0.00000000 0 0.00000000
#> AR71 0.00000000 0 0.00000000 0.00000000 0.00000000 0 0.00000000
#> AR26 0.02702703 0 0.02702703 0.02702703 0.05405405 0 0.00000000
#> AR54 0.04347826 0 0.00000000 0.04347826 0.00000000 0 0.00000000
#> AR60 0.00000000 0 0.00000000 0.07692308 0.00000000 0 0.07692308
#> AR70 0.00000000 0 0.00000000 0.00000000 0.00000000 0 0.00000000
#> Hier.pili Homo.alpi Leon.pyre Ligu.muto Lloy.sero Minu.sedo Minu.vern
#> AR07 0 0.00000 0 0.00000000 0.00000000 0.06666667 0.06666667
#> AR71 0 0.00000 0 0.04347826 0.04347826 0.00000000 0.00000000
#> AR26 0 0.00000 0 0.00000000 0.00000000 0.00000000 0.02702703
#> AR54 0 0.00000 0 0.04347826 0.00000000 0.00000000 0.04347826
#> AR60 0 0.00000 0 0.00000000 0.00000000 0.00000000 0.07692308
#> AR70 0 0.03125 0 0.06250000 0.03125000 0.00000000 0.00000000
#> Phyt.orbi Plan.alpi Poly.vivi Pote.aure Pote.cran Pote.gran Puls.vern
#> AR07 0 0 0.06666667 0.00000000 0.00000000 0 0.00000000
#> AR71 0 0 0.04347826 0.00000000 0.00000000 0 0.00000000
#> AR26 0 0 0.02702703 0.05405405 0.02702703 0 0.05405405
#> AR54 0 0 0.00000000 0.00000000 0.00000000 0 0.00000000
#> AR60 0 0 0.07692308 0.00000000 0.00000000 0 0.00000000
#> AR70 0 0 0.03125000 0.00000000 0.00000000 0 0.00000000
#> Ranu.kuep Sagi.glab Sali.herb Sali.reti Sali.retu Sali.serp Saxi.pani
#> AR07 0 0 0 0.00000000 0.00000000 0.00000000 0.06666667
#> AR71 0 0 0 0.04347826 0.08695652 0.04347826 0.00000000
#> AR26 0 0 0 0.00000000 0.00000000 0.00000000 0.00000000
#> AR54 0 0 0 0.00000000 0.00000000 0.00000000 0.08695652
#> AR60 0 0 0 0.00000000 0.00000000 0.00000000 0.07692308
#> AR70 0 0 0 0.06250000 0.06250000 0.00000000 0.03125000
#> Sedu.alpe Semp.mont Sene.inca Sibb.proc Sile.acau Thym.poly Vero.alpi
#> AR07 0 0.00000000 0 0 0.06666667 0.00000000 0
#> AR71 0 0.04347826 0 0 0.04347826 0.00000000 0
#> AR26 0 0.02702703 0 0 0.02702703 0.00000000 0
#> AR54 0 0.04347826 0 0 0.00000000 0.08695652 0
#> AR60 0 0.00000000 0 0 0.00000000 0.00000000 0
#> AR70 0 0.03125000 0 0 0.06250000 0.00000000 0
#> Vero.alli Vero.bell Myos.alpe Tara.alpi Scab.luci Anth.alpe Oxyt.camp
#> AR07 0 0.00000000 0.00000000 0 0.00000000 0.00000000 0.06666667
#> AR71 0 0.00000000 0.00000000 0 0.00000000 0.04347826 0.00000000
#> AR26 0 0.00000000 0.02702703 0 0.02702703 0.00000000 0.02702703
#> AR54 0 0.04347826 0.04347826 0 0.00000000 0.00000000 0.00000000
#> AR60 0 0.00000000 0.00000000 0 0.00000000 0.00000000 0.00000000
#> AR70 0 0.03125000 0.00000000 0 0.00000000 0.00000000 0.00000000
#> Oxyt.lapp Lotu.alpi Trif.alpi Trif.badi Trif.thal
#> AR07 0.06666667 0 0 0 0
#> AR71 0.04347826 0 0 0 0
#> AR26 0.00000000 0 0 0 0
#> AR54 0.04347826 0 0 0 0
#> AR60 0.07692308 0 0 0 0
#> AR70 0.03125000 0 0 0 0